1. Field of the Invention
The present general inventive concept relates to a virtual sound system, and more particularly, to an apparatus and method to cancel crosstalk between 2-channel speakers and two ears of a listener and a stereo sound generation system using the same.
2. Description of the Related Art
A stereo sound system disposes a sound source in a predetermined position of a virtual space through a headphone or speaker and provides a directional perception, a distance perception, and a spatial perception as though a sound is actually being heard from a place at which a virtual sound source of the sound is located. Generally, a stereo sound is implemented by a binaural synthesis filter using a head related transfer function (HRTF) that is an acoustic transfer function between sound sources and eardrums. A stereo sound using the binaural synthesis filter shows the best performance when a signal is reproduced through a headphone. However, if the signal is reproduced through two speakers, crosstalk between the two speakers and two ears of a listener occur such that a stereo perception is degraded. Accordingly, a crosstalk canceller cancels the crosstalk between both signals so that a signal reproduced through a left speaker is not heard in a right ear of the listener and a signal reproduced through a right speaker is not heard in a left ear of the listener.
A technology related to this crosstalk canceller is described in U.S. Pat. No. 6,668,061 B1 (filed 18 Nov. 1998, entitled, “CROSSTALK CANCELLER”).
FIG. 1 illustrates a conventional crosstalk canceller. The crosstalk canceller of FIG. 1 is called a lattice structure and includes four filters 142, 143, 144, and 145.
Referring to FIG. 1, a left input signal 140 (BL) is convoluted through a filter 142, and a right input signal 141 (BR) is convoluted through a filter 144. Subsequently, the two convoluted signals are added to each other by an adder 150 and reproduced as a left output signal 152 (SL). In addition, the right input signal 141 (BR) is convoluted through a filter 145, and the left input signal 140 (BL) is convoluted through a filter 143. Subsequently, the two convoluted signals are added to each other by an adder 151 and reproduced as a right output signal 153 (SR).
In the cross-talk canceling method illustrated in FIG. 1, a convolution operation is performed four times with respect to the four filters 142, 143, 144, and 145. Thus, a large amount of computation is required when the order of each filter is high. Accordingly, in the conventional crosstalk canceller, it is difficult to perform convolution in a time domain and convolution should be performed in a frequency domain. However, since convolution in the frequency domain requires a large-size memory, the size of a program must also be increased.